sysfs: update Documentation

Make editing corrections and updates to sysfs.rst:

- spell "sysfs" consistently (vs. "Sysfs")
- align field names in a struct
- fix some punctuation and grammar
- list more /sys top-level subdirectories
- change 'fuse.txt' to 'fuse.rst' (although I don't see where the
  example is)

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20221104003921.31616-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>